Endocrinology Flashcards
explain the pathophysiology of type 1 diabetes
insulin deficiency, due to autoimmune destruction of insulin-secreting pancreatic beta cells
(islet cells: alpha cells = glucagon, beta cells = insulin)
explain the pathophysiology of type 2 diabetes
insulin resistance develops - body can no longer produce enough insulin to cope with the high levels of glucose entering the body so the cells become resistant to insulin’s effects.
there is hypersecretion of insulin, by a depleted number of beta cells, so the insulin levels are increased by not enough to control glucose homeostasis.
hyperglycaemia and lipid excess are toxic to beta cells so insulin secretion then drops.
what is the classical triad of symptoms for a presenting type 1 diabetic? what causes each of these
polyuria - due to osmotic diuresis from blood glucose exceeding the tubular reabsorption capacity.
polydipsia - due to fluid and electrolyte loss.
weight loss - fluid depletion and accelerated breakdown of fat and muscle.
also lethargy, DKA
give 3 complications a type 2 diabetic may present with
recurrent staphylococcus skin infections (also thrush, UTIs), retinopathy, polyneuropathy, erectile dysfunction, arterial disease e.g. MI.
sometimes just picked up on glucose testing. may get polyuria, polydipsia etc as well.
what investigation is used to measures long term glucose control? what are the normal and diagnostic values?
HbA1c - glycosylated haemoglobin - glucose is taken up by haemoglobin and remains in blood for 8-12wks - high blood glucose over that period shows up as a raised HbA1c.
diagnostic value is >48mmol/mol.
what is the WHO diagnostic criteria for diabetes mellitus ?
hyperglycaemic symptoms - polyuria, polydipsia, unexplained weight loss, visual blurring, genital thrush, lethargy AND:
fasting plasma glucose >7.0mmol/L OR.
random plasma glucose >11.1 mmol/L.
describe the general, non-pharmacological management of diabetes mellitus
risk factor management (esp. BP control!).
diabetes education, diet and exercise e.g. educate on self-adjusting doses in T1 (DAFNE).
frequent self-monitoring of blood glucose (if IDDM) and long-term monitoring of HbA1c.
maximise glucose control.
what are the steps in the pathway for managing T2DM
check this is up to date (NICE)
1) lifestyle and diet changes for 6/52, inform DVLA. low GI/dairy/fat/sugar diet, aim for 5-10% wt loss
measure HbA1c 3-6mthly initially then 6/12 (aim 48/6.5%)
2) single drug therapy - metformin ideally, increase gradually over few weeks (GI SEs). aim 6.5%/48.
3) dual therapy only if >58/7.5%: gliptin or sulfonylurea or pioglitazone, target 53/7%.
4) triple therapy if still not under 58/7.5%:
- metform + sulfonylurea + pioglitazone
- metformin + sulfonyurea + gliptin
- start insulin
5) insulin
* if metformin CI do any 1 drug –> any 2 –> insulin
how does metformin work?
biguanide.
reduces rate of gluconeogenesis, reducing hepatic glucose output.
increases insulin sensitivity (GLUT4).
CI - CKD, eGFR <30.
NO weight gain or hypos, but can cause lactic acidosis.
SEs - GI upset** 20% intolerable!
how do sulfonylureas work?
oral hypoglycaemics
binds to channels on beta
cells to increase fusion of insulin granulae with cell membrane - INCREASES PANCREATIC INSULIN SECRETION.
SEs- hypos and weight gain.
CI pregnancy
how does pioglitazone work?
increases insulin sensitivity - promotes glucose consumption by muscles.
SE - wt gain, fluid retention, osteoporosis.
CI - heart failure and osteoporosis.
what are the differences in onset between type 1 and type 2 diabetes?
type 1 - adolescent onset usual.
type 2 - onset usually >40yrs.
type 1 is linked to HLA D3 and D4, type 2 has no HLA association.
what are the differences in how type 1 and type 2 diabetes present?
type 1 will present with polydipsia, polyuria, weight loss, ketonuria etc.
type 2 presents asymptomatically (picked up on blood test), or with complications e.g. MI, recurrent infections
what lifestyle factors is type 2 diabetes associated with?
obesity, lack of exercise, calorie and alcohol excess.
list some possible causes of DM
drugs - steroids, anti-HIV drugs, antipsychotics, thiazides.
pancreatic - pancreatitis, surgery, trauma, pancreatic destruction (haemachromatosis, CF), pancreatic cancer.
Cushing’s disease.
Acromegaly.
Phaeochromocytoma.
Hyperthyroidism.
Pregnancy (gestational diabetes).
give 3 risk factors for type 2 DM
overweight/obese. central adiposity. Asian background. Age >40yrs. FHx. gestational diabetes.
what are the main different types of insulin regimes? what are the important SEs to be aware of for insulin?
1) Once-daily- ;ong or int at bedtime - only suitable T2DM
2) Twice-daily - pre breakfast/evening meal
3) Basal-bolus - long or int at bedtime with rapid/short to cover meals
4) Continuous subcut or insulin pump - if very poor control
hypos and lipodystrophy
give examples of possible injection sites for insulin. why is it important they are rotated regularly?
outer thigh, abdomen, arm.
rotating reduces risk of infection and lipohypertrophy (lipohypertrophy).
what are the main long term complications of diabetes mellitus
retinopathy, neuropathy, nephropathy, skin infections.
also increased risk of MI, stroke etc
describe the symptoms of hypoglycaemia
autonomic - sweating, anxiety, hunger, tremor, palpitations, dizziness.
neuroglycopenic - confusion, drowsiness, visual trouble, seizures, coma
how would you treat hypoglycaemia?
conscious? - 10-20g short acting carb e.g. Lucozade, x3 glucose tablets, glucogel (then some toast or something for long-acting carbs!!)
unconscious? safe airway consider glucogel, IM glucagon probs best!
what is a hypoglycaemic coma? how would you treat it?
rapid onset of hypoglycaemia preceded by aggression, sweating, high pulse, seizures - leading to loss of consciousness.
treat with IV glucose or IM glucagon - should recover promptly.
sugary drinks and a meal once conscious.
how does DKA present?
abdo pain + vomiting
polyuria, polydipsia, dehydration Kussmaul breathing (deep hyperventilation to correct acidosis) Acetone breath (pear drop - ketones)
what causes diabetic ketoacidosis?
there’s an excess glucose, but due to lack of insulin this can’t be taken up by cells to be metabolised - body pushed into starvation-like state.
ketoacidosis is the only alternative metabolic pathway.
results in severe acidosis.
does diabetic ketoacidosis generally occur in type 1 or type 2 diabetics?
type 1 - rare in type 2.
give 3 possible triggers/precipitants of DKA
missed insulin, infection, intoxication, ischaemia, infarction
what would you find on investigation of a patient presenting with DKA?
high plasma glucose (>11)
high plasma ketones >3 mmol/L
ABG - metabolic acidosis (pH <7.3)
urine dip - ketones ++ and glucose.
give 3 possible complications of DKA
cerebral oedema, aspiration pneumonia, **hypokalaemia (caused by you giving fluids and insulin wrong!!!), hypomagnesaemia, hypophosphataemia, thromboembolism
how would you manage a patient presenting with DKA?
ABCDE, catheterise, sats etc
need IV fluids, insulin to drop blood glucose - but will drop potassium so add to fluids. follow hosp. protocol, usually end up needing infusion of insulin and glucose after a bit.
IV normal saline 1L in 1hr, in 2hr, in 2, in 4, in 4, in 6 - switch to 5% dextrose when glucose is <12.
fixed rate IV insulin infusion = 0.1U/kg/hr, add glucose when drops <12
monitor K+ and add to fluids - if >5.5 nil, 3.5-5.5 add 40mmol/L to infusion solution, <3.5mmol/L senior review,
might use IV bicarb for acidaemia.
monitor - electrolytes and bicarb, pH etc every 1-2hrs. glucose hourly, fluid balance, ECG for hypokalaemia.
is hyperglycaemic hyperosmolar non-ketotic (HONK) state/coma more likely to affect a type 1 or type 2 diabetic?
type 2
how would a hyperosmolar hyperglycaemic state present?
longer history (1wk) with marked dehydration and raised glucose.
stupor/coma.
impairment of consciousness is directly related to degree of hyperosmolality.
very high blood glucose >40, v high serum osmolality.
how would you manage a HONK patient?
treat cause, ABCDE etc
safely normalise osmolality- replace fluid and electrolytes
normalise blood glucose.
what are patients with HONK at particular risk of?
cerebral oedema, central pontine myelinosis
also strokes, MI etc
how might diabetic neuropathy present? how would you manage it?
stocking and glove distribution of loss of sensation, absent ankle jerks, deformities. may develop ulcers and ischaemia if there’s accompanying peripheral vascular disease.
special foot care and diabetic shoes needed.
control pain with:
paracetamol => amitriptyline => gabapentin => baclofen
explain the disease process underlying Graves’ disease
autoimmune - serum IgG antibodies bind to TSH receptors causing thyroid growth and overstimulation of thyroid hormone
causes 75% of hyperthyroidism
associated with thyroid eye disease.
worsened by radio-iodine and smoking.
name 3 triggers for the development of Graves’ disease
stress, infections, childbirth, other autoimmune diseases
if you measures TSH and T3/T4 in Graves’ disease, what would you expect to see? other Ix?
suppressed TSH, high T3/T4.
auto-antibodies: anti-TSHR (99% in Graves!) + anti-Tg + anti-TPO.
USS if ? cancer, radioisotope uptake scan (hot = overactive, no uptake in DeQuervain’s)
what are the features of thyroid eye disease?
lid lag, lid retraction, ophthalmoplegia, exophthalmos, gritty eyes, diplopia, loss of colour vision, conjunctival oedema, papilloedema
give 4 clinical features of hyperthyroidism
weight loss diarrhoea heat intolerance increased appetite palpitations tachycardia irritability tremor hyper-reflexia lid lag oedema sweating
eye disease in Graves’
list 3 causes of hyperthyroidism, not including Graves disease
toxic multinodular goitre toxic adenoma
amiodarone
post partum thyroiditis, iodine excess (e.g. contaminated food, contrast media).
overtreatment of hypothyroidism
secondary - TSH secreting pituitary adenoma.
describe the production and general action of thyroid hormones
stimulated by TSH produced by pituitary gland.
thyroid gland secretes mostly thyroxine (T4) + some of the active triiodothyronin (T3).
most T3 is produced by peripheral conversion of T4.
gland requires iodine to produce the hormones.
act on nearly every cell, controlling metabolism - increase BMR.
what would you see on blood tests in hyperthyroidism?
TSH low - suppressed.
raised T4 and T3.
thyroid autoantibodies seen in Graves’.
outline medical management of hyperthyroidism
beta blockers (propranolol) for rapid symptom control. lubricating eye drops if Graves/eye disease
anti-thyroid drugs - carbimazole and propythiuracil.
- carb. = start 10-20mg/day and titrate based on mthly TFT
- propyl. can cause liver failure so only used in pregnancy and thyroid storm.
“block and replace” = carbimazole + thyroxine used to strike fine balance. can sometimes just carefully titrate.
usually euthyroid at 4-8wks, then can reduce till lowest dose. remission at 18mths- try stopping drugs.
WARNNG - sore throat - anti-thyroid drugs can myelosuppress –> agranulocytosis + neuropenic sepsis!!!
what does a thyroidectomy risk?
hoarseness due to damage to recurrent laryngeal nerve.
hypoparathyroidism.
name 2 possible complications of hyperthyroidism
heart failure, angina, AF, osteoporosis, ophthalmopathy, gynaecomastia
what is thyroid acropachy? give 2 features
a dermopathy associated with Graves’ disease.
CLUBBING, painful digit swelling
give 4 symptoms of hypothyroidism
weight gain decreased appetite lethargy low mood cold intolerance constipation hoarse voice decreased memory/cognition cramps and weakness
give 4 signs of hypothyroidism
BRADYCARDIC: Bradycardia. Reflexes relax slowly. Ataxia Dry thin hair/skin Yawning/drowsy/coma Cold hands ± low temp. Ascites ± non-pitting oedema ± pericardial effusion. Round puffy face/double chin/obese. Defeated demeanour Immobile CCF (congestive cardiac failure)
give 3 causes of hypothyroidism
Hashimoto’s thyroiditis (most common UK), iodine deficiency (most common worldwide), post-thyroidectomy/radioiodine treatment,
primary atrophic hypothyroidism, antithyroid drugs.
what would you find on investigation of a patient with hypothyroidism?
high TSH, low T3/free T4.
may see TSH deficiency if secondary hypothyroid (hypopituitary, hypothalamic)
how would you treat hypothyroidism?
levothyroxine (T4) - given for life, monitor TSH levels, increase dose when pregnant
initial dose = 50-100mcg, step up by 25-50 depending on TFT every 3-4/52
risk of osteoporosis and arrhythmias if overmedicate
annual TFTs once stable.
if subclinical then just monito TFT every 6-12/12 and treat is TSH >10
what is Hashimoto’s thyroiditis? what conditions are associated with it?
a primary, autoimmune thyroiditis. cause hypothyroidism (or euthyroidism), with goitre that is due to lymphocytic and plasma cell infiltration. more common in women aged 60-70yrs.
AI disease - T1DM, Addison’s, pernicious anaemia.
as it’s most common cause of hypothyroid in UK - consider these AI diseases in all hypothyroidism.
give 3 diseases associated with hypothyroidism
autoimmune hypothyroidisms are associated with other autoimmune disease - type 1 DM, Addison’s, pernicious anaemia.
Turner’s and Down’s syndromes.
CF, primary biliary cirrhosis, ovarian hyperstimulation, pregnancy problems (eclampsia, anaemia, prematurity, low birthweight etc).
how can thyroid cancer present? treatment options? what blood marker used to monitor?
thyroid nodules and cervical lymph nodes
total thyroidectomy, radioiodine to kill residual cells.
annual thyroglobulin tests to detect recurrence.
where are the common metastases sites for papillary and follicular carcinomas?
lungs and bones
how would you manage a thyroid carcinoma?
total thyroidectomy and lymph node clearance ± radioiodine ablation
what are the different types of thyroid cancer?
70% papillary - young F, good prognosis
20% follicular
5% medullary (part of MEN2)
give one physiological and one pathological cause of goitre
physiological - puberty, pregnancy.
pathological - iodine deficiency, high dose of carbimazole/propylthiouracil
if goitre became painful, what could be the cause?
bleeding, thyroiditis, malignancy
give 2 indications for surgery in goitre
malignancy, pressure symptoms, toxic nodule, cosmetic reasons
what does the adrenal cortex produce, and what do they do?
steroids.
Salt - Sugar - Sex (it gets sweeter as you go deeper)
mineralocorticoids (e.g. aldosterone) - control sodium and potassium balance.
glucocorticoids (e.g. cortisol) - affect carbohydrate, lipid and protein metabolism.
androgens - sex hormones.
how is the adrenal cortex stimulated to produce cortisol/androgens?
corticotrophin-releasing factor (CRF) from hypothalamus stimulates ACTH secretion from pituitary - stimulates cortisol and androgen production.
what is Cushing’s syndrome?
clinical state produced by prolonged glucocorticoid excess –> of normal feedback mechanisms of the hypothalamo-pituitary-adrenal axis and loss of circadian rhythm of cortisol secretion
EXCESS CORTISOL/corticosteroids
what is the main cause of Cushing’s syndrome?
oral steroids
what are the two classes of causes of Cushing’s syndrome?
increased circulating ACTH from a pituitary/ectopic tumour with glucocorticoid excess - ACTH dependent.
primary excess of cortisol secretion by an adrenal tumour or nodular hyperplasia with ACTH suppression - ACTH independent.
give 3 symptoms of Cushing’s syndrome
weight gain stretch marks red puffy, round face tanned skin - Cushing's disease muscle weakness depression tiredness
give 3 signs of Cushing’s syndrome
central obesity, moon face and buffalo hump. skin and muscle atrophy. bruising. purple abdominal striae (stretch marks). osteoporosis hypertension. pigementation, in ACTH dependent causes.
what is the specific test used for Cushing’s syndrome and what would you expect the results to be? other tests?
first line - 1mg overnight dexamethasone suppression test, measure cortisol at 8am.
second line = 48h 2mg dexamethsone test - this would normally suppress cortisol, but in Cushing’s you see normal/low ACTH and high cortisol.
failure to suppress <50nmol/L on either is +ve.
elevated serum glucose.
24h urinary free cortisol (high in 2/3 samples).
what is Cushing’s disease?
bilateral adrenal hyperplasia due to ACTH-secreting pituitary adenoma
give 2 ACTH-dependent causes of Cushing’s syndrome
Cushing’s disease, ectopic ACTH production
give 2 ACTH-independent causes of Cushing’s syndrome
adrenal adenoma/cancer, adrenal nodular hyperplasia, iatrogenic - STEROIDS.
why would you not test for Cushing’s by taking random plasma cortisols?
can be misleading - variation due to illness, time of day, and stress (e.g. venepuncture!)
how would you manage a patient with Cushing’s syndrome?
stop steroids if possible.
cushing’s disease - transphenoidal pituitary adenomectomy ± radiotherapy. last resort - bilateral adrenalectomy.
what is the main cause of acromegaly?
pituitary adenoma - secretes excess GH
give 4 symptoms of acromegaly
persistent numbness and tingling in hands and feet headache amenorrhoea sweating arthralgia increase in weight low libido, backache "my rings and shoes don't fit anymore"
give 4 signs of acromegaly
growth of hands, feet and jaw coarsening face, wide nose macroglossia darkened skin obstructive sleep apnoea goitre carpal tunnel syndrome puffy lips laryngeal dyspnoea
what cardiac disease can acromegaly cause?
hypertrophic cardiomyopathy
what would you find on blood tests in acromegaly? what’s the diff. between acromegaly and Giantism?
raised IGF-1 (main tissue mediator of GH), GH and prolactin - secreted by adenoma
acromegaly = overgrowth of all organ systems, joints, soft tissues by IGF1. Giantism = excess GH or IGF1 before closure of epiphyseal plates.
what specific test would you do to confirm a diagnosis of acromegaly? what else can be helpful when trying to diagnose acromegaly?
oral glucose tolerance test - diagnostic if GH is not suppressed by the glucose.
old photos of the patient.
what is the 1st line treatment of acromegaly?
if that is CI, what would you try?
transphenoidal surgery.
if CI - somatostatin analogues (GH is inhibited by somatostatin) - lanreotide, ocreotide.
GH antagonist - pegvisomant.
what are the metabolic actions of GH?
stimulates IGF-1 to be produced and secreted by the liver.
increases collagen and protein synthesis, opposing the action of insulin (same as glucagon).
promotes retention of calcium and nitrogen.
mainly secreted nocturnally.
explain the pathophysiology underlying Conn’s syndrome
excess aldosterone production causing sodium retention, potassium loss and less renin release - causes hypertension.
explain the renin-angiotensin-aldosterone system
renin is secreted by the kidneys in response to hypoperfusion of the kidneys, which then cleaves angiotensinogen into angiotensin I, which is an inactive form.
angiotensinogen is made in the liver, and circulates in the plasma.
angiotensin I is converted by ACE (produced in lungs) into angiotensin II in the lung and vascular endothelium.
angiotensin II causes vasoconstriction and stimulates the zona glomerulosa to increase its production of aldosterone - raises blood pressure and sodium retention - increasing blood volume.
what is Conn’s syndrome?
a cause of hyperaldosteronism - there’s an aldosterone-producing adrenal adenoma
what are the 2 main causes of primary hyperaldosteronism?
Conn’s disease (adrenal adenoma) and bilateral adrenocortical hyperplasia.
hyperaldosteronism/Conn’s is normally asymptomatic and picked up on a routine test, what test is this?
testing BP - hypertension.
before you begin to investigate hyperaldosteronism/Conn’s, what medications should you stop?
ACEi, beta-blockers, spironolactone, ARBs
what are the sodium and potassium levels seen in patients with hyperaldosteronism/Conn’s, and how does this present?
high serum sodium, low serum potassium.
features - headaches, polyuria (compensatory), muscle weakness, tetany, nocturia.